The present invention relates to a noise reduction device for use in a reciprocating compressor; and, more particularly, to a noise reduction device for use in a hermetic reciprocating compressor employed in a refrigerator, the noise reduction device incorporating therein a side-branch silencer formed in a discharge valve assembly.
Compressors often generate undesirably exceedingly high levels of noise. A certain kind of reciprocating compressor often produces noise having band ranges lower than about 4 kHz. Of the noises produced, noises having frequencies of 3.15 kHz and 2.5 kHz are most problematic because human ears are generally more sensitive to noises at these frequencies.
There is shown in FIGS. 1a through 2, one of the prior art hermetic reciprocating compressors. A main body of the compressor is mounted within a pair of cases 10 and 20. The compressor is largely divided into a frame 30, a motor 40 which rotates a shaft 60 and a machinery part 50 which transforms a rotational movement of the shaft 60 into a rectilinear movement of a piston 120, allowing the piston 120 to compress refrigerant gases and discharge the same.
The frame 30 supports the motor 40 and the machinery part 50 through supporting a side stopper 70 and a coil spring 80 which function as a cushioning means and a noise attenuation means, respectively.
The machinery part 50 includes a cylinder 110, the piston 120 rectilinearly moving within the cylinder 110, and a piston rod 130 connecting the piston 120 to a crank 61 of the shaft 60 to transform a rotational movement of the shaft 60 into a rectilinear movement of the piston 120. The rectilinear movement of the piston 120 within the cylinder 110 compresses refrigerant gases introduced into the cylinder 110 and discharges compressed gases therefrom.
A valve plate 140 having an intake port and a discharge port is mounted at one side of the cylinder 110. An intake muffler 150 and a discharge muffler 160 for guiding an intake and a discharge process of the refrigerant gases, respectively, are formed outside the valve plate 140. An intake and a discharge pipe 170 and 180 are connected to the intake and the discharge muffler 150 and 160, respectively. The discharge muffler 160 into which the refrigerant gases are compressed to a high temperature and a high pressure are discharged from the cylinder 110, attenuates the noise caused by a pulsation of the refrigerant gases which is discharged from the cylinder 110.
The discharge muffler 160 is provided with a muffler plate 182 having an intake hole through which the refrigerant gases are introduced into the cylinder 110, a discharge hole and a delivery hole (not shown), and a valve cover 184 having a first room communicating with the discharge hole and formed with an internal plate and an external plate. The discharge muffler 160 is also provided with a muffler cup 190 connected to the delivery hole of the muffler plate 182 and having a second room communicating with the delivery hole and the discharge pipe 180 connected to the muffler cup 190, and a noise reducer 200 connected to a side of the muffler cup 190 through a connection pipe 210.
In the discharge muffler 160 described above, when the piston 120 is reciprocated by the shaft 60 to compress the refrigerant gases, the compressed refrigerant gases are discharged through the discharge hole of the muffler plate 170 into the first room of the valve cover 184, and then are delivered through the delivery hole, to the muffler cup 190 and finally to the discharge pipe 180 in that order. Sounds generated by the pulsation of the refrigerant gases being discharged and by the refrigerant gases colliding on valves are attenuated by the noise reducer 200 connected to the muffler cup 190 via the connection pipe 210.
The noise reducer 200 described above, however, has shortcomings in that its efficiency in attenuating the noise is low and that it requires a large mounting space therefor in the hermetic reciprocating compressor.
It is, therefore, a primary object of the invention to provide a noise reduction device having an enhanced efficiency in attenuating a noise, especially, a noise at a particular frequency, without demanding any external mounting space for an installation thereof.
The above and other objects of the invention are realized by providing a noise reduction device for use in a hermetic reciprocating compressor, wherein the hermetic reciprocating compressor is provided with a discharge valve assembly having a discharge muffler, a gasket, a discharge valve piece and a valve plate, the discharge valve assembly being mounted on a cylinder block, the noise reduction device further comprising: a side branch silencer formed within a discharge valve assembly.